Nonintermittent motion-picture projector



May 28, 1946. c. D. MlLLER NONINTERMITTENT MOTION-PICTURE PROJECTORFiled July 1, 1940 INVENTR CEARCy D. M/.LLER WFM A'n'o Ey Patented May.28., 1946 UNITED STATE 8 Claims.

under the (Granted amended April This invention relates to a devicecapable of projecting motion pictures without stopping or varying thespeed of the motion-picture iilm dur ing the process of projection andwithout at any time cutting off or varying useful illumination reachingthe projection screen.' It is essentially a reversal of a modified form'of the high-speed motion-picture camera covered in my copendingapplication Serial No. 340,068.

, It has long been understood by those skilled in the art ofmotion-picture projection that the nonto offer as compared with theintermittent type if only a, non-intermittent projector could bedesigned which would give a projected image with definition equal vtothat of images projected by the highly developed intermittentprojectorsnow in use, and which would be no more expensive to manufacture. Theseadvantages include the following: The non-intermittent projector is lessnoisy in operation. The non-intermittent projector causes less wear andtear on the film, due to the elimination of the necessity of rapidacceleration and deceleration 'of the film. Use of the non-intermittentprojector makes it vpossible to place the sound gate and the opticalgate at the same position along the film. This greatly simpliiies theoperators' task of through the projector, eliminates the possibility ofhis getting sound and optics incorrectly phased, and contributes toreduction of film lwear and tear. It also does away with thedisplacement of the sound track relative to the photographs on the nlm,which eliminates difficulty in assembling and in altering iilms. Use ofa non-intermittent screen without interruption; as this device does,permits use of a less powerful light source than is at present used ormakes possible a more brilliant illumination of the screen with use ofthe same light source. (Brilliancy of illumination as referred to hereis thequantity f '1 Il@ T o where I is the intensity of screenillumination at any instant expressed as a function gli T is the'apparent brilliancy of the projection screen as seen by the eye.) lesseye strain results from the intensity of the s PATENT NoNrN'rEnMrr'rEN'rMOTION-morons PROJECTOR Cearcy D. Miller, Hampton, Va. Application July1, 1940, Serial No. 343,417

act of March 3, 1883, as 30, 1928; 370 0. G. 751) Sreen.

intermittent projector has important advantages threading nlm projectorwhich throws light on the projection of time t and v T islthe time of acomplete cycle of operation.

.trayed on of even high due to the projection of steady light ducing athe non-intermittent one picture frame picture frame gradually fades in,in ducing sudden shift trom.one picture and fade termittent projector.

-With the foregoing the invention consists in the con bination anddescribed and illustrated in Fig. lisa Fig. 2 is a side-elevation of aporti ror drum 82 as seen projected on 1, with cut-away portions shownIt is also possible `that iaden and fadeprojector, that gradually fadeout apparent reason why made as good with this device As for as withline OFI-lcs frequency flicker on the the apparent out effect with is byhaving as the next stead of proframe to -out eilect can the quality theprojection screen this could not be the inand other objects in view,struction, com arrangement of parts hereinafter the drawing, in which,horizontal section through the device,

on of the mir- 2-2 of Fig.

in cross-section.

Fig. 3 is a side-elevation of iilm gate 1| as seen projected on line 3-3Fig. 4 seen projected on line Referring particularly to Fig.

frame of merels IBI, |62, |83, |64, |65, and

8B or stationary indicates the main projections of frame attachedthereto. Rotatably tions |63 and IM 'of by direct-connected motor 15 ormeans. Rigiciiy mounted on wheel 12 which draws shown), through nlm gatewhich .is rigidly 12 nlm M is wound t0 passing over pulleys ly attachedto shafts 13 ratio of that take-up reel 11 will take through byvsprocket 12,

of Fig. 1. is a side-elevation of fram I-l of Fig. 1.

film 8| from mounted in pr frame 6I. After passage around sproc ontake-up reel 18, with take-up reel 11, is driven by s 10 and 19, and 18,r diameters of pulleys 18 an nlm as i even when of nlm 8| wound on asmore nlm slippage of the spring belt 8l.

1, the

this device.

|66 indicate parts rigidly ing gate 88 as numeral 68 mounted inprojecother frame B8 is shaft 13, driven suitable shaft 13 is sprockete1 11. The necessary slower turninirtrI i 11 whi is rotatably 8. Shaftfeed reel (not Figs. 1 ejection |6| of ket wheel and ch is espectively.The d ,19 -is such ast as gear 1l,

meshing with bevel gear 91, mounted on shaft 85, which in mounted inprojection |92 of frame 98. Also rigidly mounted on shaft 99 is bevelpinion gear 99, meshing with crown gear |29, which is rigidly mounted onshaft 83, which in tu'rn is rotatably mounted in frame 99. Also rigidlymounted on shaft 98, with key 9|, is mirror wheel 92. A projection of aportion of this mirror wheel 2 2 of Fig. 1 is shown the numerals 99 and9| which is rigidly turn is rotatably in Fig. 2. In this figure,

indicate mirror surfaces which may be either polished surfaces of themetal of mirror wheel 92 or individual mirrors fastened by any suitablemeans to the mirror wheel. They may also be glass prisms such as used inthe high-speed motion-picture camera described in the patent applicationabove referred to. The angle a in Fig. 2 between mirror surfaces 99 and9| should be 90 as nearly as possible.

An alternative arrangement may be used involving movable mirror 92, Fig.2.` This mirror is so arranged as to pivot about its edge |91 whichprojects into a groove in mirror face |98. To the back of movable mirror82 is fastened one end of coil spring 95, which extends through hole |99drilled through the metal of mirror wheel 82. 'I'he other end of coilspring 99 is attached to lug 99, which serves simply to hold the springtaut. This arrangement is for the purpose of holding movable mirror 92firmly against adjusting screw 93, which extends through hole |19 inmirror wheel 82, screwing into enlarged threaded portion of this hole1|. Screw 98 is locked in position by locknut 94, in order to form alocking surface for locknut 94. By means of adjusting screw 98, and theother parts just described, the movable mirror 92 may be adjusted toprovide an extremely accurate right angle between mirror faces 92 and|98. This arrangement is intended merely as a schematic illustration asto how adjustable mirror faces might be provided, and it is not to beunderstood as limiting this device to the use of this particular type ofadjusting mechanism.

Referring again to Fig. 1 of ratios of sears 14 and 81 and gears 99 and|20 must be such that sprocket wheel 12 makes N complete revolutions foreach single revolution of mirror wheel 82 where ni being the number offaces 90 or the number of faces 9| on mirror wheel 92, n: being thenumber of teeth on one side of sprocket wheel '|2, and n: being thenumber of perforations per picture frame on one side of film 8|. Filmmetering sprocket 12 must be so phased with mirror wheel 92 that theexact center of an individual frame of film 9| will cross axis X-X,which is in the plane of Pig. 1, at the same instant that the 90 anglebetween one pair of faces 9|)l and 9| on mirror wheel 82 crosses thesame axis.

Numeral 99 indicates a light source, on axis X-X, rigidly secured inprojection |9| of frame 98. Numeral. 1l indicates a reflector rigidlysecured in frame 99 and of such focal length as to form an'image oflight source 99 at the center lol' lens |19, which is rigidly mounted inprojection I9! of frame "with its optical axis identical with axis XX.The light cone extending from reflector 19 to lens ||9 is large enoughin crosssection at ture |13 in thegate, see Fig. 3. The lens |19 is ofsuch focal length and is so placed as' to form a countersink |12 beingprovidedthe drawing, the

on line will be referred to as mirror pair No. 1, and

just above No. 2 will an image of the pictures appearing on nlm 8l atthe framing gate 88 (which is rigidly mounted in projection |99 of frame98) after reflection by mirrors 90 and 9i onomirror wheel 82 from axisX-X to axis Y-Y, axis Y--Y being in the plane of Fig. 1. Itis also ofsuch focal length and is so placed that the ratio of size of image atframing gate 88 to size of image on film 9| is where :l: is the distancebetween two successive mirror pairs 9|) and 9| on mirror wheel 82 and yis the height of a single picture frame on the illm. Lens 89 is rigidlymounted in frame 98, with its optical axis identical with axis YY, andis of such focal length and is so placed as to form on the projectionscreen an image of the aperture The bisector of angle 1 see Fig.l,.between axes X-X and Y-Y is per pendcular to the intersection offaces of mirror wheel 82 at the time this intersectio crosses theseaxes.

As stated above, film-metering sprocket 12 an mirrorwheel 82 are sophased that the line intersection of a particular mirror pair 99 and Ion mirror wheel 82 crosses axis X--X at the ex instant the center of onfilm 8| crosses the same axis. In the dis sion which follows, thisparticular picture fr will be referred to as picture frame No. 2 andparticular mirror pair will be referred to as mir pair No. 2. Thepicture frame next above pict l frame No. 2 will be referred to aspicture fra No. i and that just below No. Z as picture fr No. 3. Mirrorpair just below mirror pair No.

be referred to as mirror p from picture frame No. 3 and falling on mipair No. 3 will be reflected to its proper position the stationary imageat framing gate 88.

gate and by projection |99 of fra 98 surrounding the gate (the openingin the g being the exact size and in the exact position the centralimage). All light coming from ture frame No. 2 and failing on mirrorpair l l, or coming from picture frame No.

ly, all light passing through framing gate 88 be brought to a focusformingT a single image the projection screen by lens 83.

In Fig. 1 .the angle v between X and Y-Y is approximately 90. The qlllit, projection as well as the desirable feature vice to use of themeans shown in Fig. 1 for carrying reflecting surfaces 9|) and 9| acrossthe axis X-X and the axis Y-Y as it is apparent that these reflectingsurfaces could be carried acrossv these axes in any one of a number ofways without conflicting with the spiritof this.

tained in this device by locating the image formed by lens I I8, Fig. 1,near the intersection of axes X-X and Y-Y, it is necessary to vconsiderin more detail the reflecting surfaces 90 and 8| of mirror wheel 82, seeFig. 2. Approximately half the light passing through a given point in'the moving film 8| and also passing through the aperture |14 in framinggate 88, see Fig. 4, will be reflected from a mirror surface 90, Fig. 2,to a mirror surface 8| and thence to aperture |14 in framing gate 88.'I'his light will hereinafter be referred to as following mirror pathNo. l. The other half of the light passing through the same point inmoving viilrn 87| through aperture. |14 in framing gate 88 will bereflected from mirror surface 9| to mirror surface 80 and thence throughaperture |14 in framing gate 88. This light 'will hereinafter bereferred to as following mirror path No. 2. If the angle between theparticular mirror surfaces 80 and 8| involved is not exactly 90 thelight following mirror path No. 1 will not reach the same point inaperture |14 of `framing gate 88 as the'light following mirror path No.2, even though it comes from the same point in the moving film 8|. Thisresults in tWo images being formed Within the aperture 14 in framinggate 88,/somewhat displaced fromv each other, and consequently the sameresult is produced on the projection screen. Now the nearer framing gate88 can be placed to the intersection of axes X-X and Y-Y the smallerwill be the separation between the two images formed by light followingmirror paths I and 2 with a given departure of the angle between mirrorsurfaces 90 and 9| from an exact right' angle. By locating the framinggate 88 in the manner shown in Fig, 1 of the drawing, the separationbetween these images can be reduced to a negligible amount with areasonable tolerance for the angle between mirror surfaces 90 and 8|. Itis not to be understood that this device is limited to the'use ofthereflecting surfaces 80 and 9| of Fig. 2 as a compensating means. It isrecognized that a similar result may be gotten by any optical devicewhich inverts a beam of lightl with respect to a neutral l plane. suchneutral plane being perpendicular to the plane of motion of the device,fixed with reference to the device itself, and parallel to the andpassing optical axis of the beam. 1t is also recognized that any suchoptical device is likelyto have aberrations due to small inaccuracies inits con' struction which can be practically eliminated by forming animage as close as possible to the position of the compensating device inthe optical path.

v Other lmodifications and changes in the num-v ber and arrangement ofthe parts may be made by those skilled in the artwithout departing fromthe nature of the invention, within the scope of what is hereinafterclaimed.

The invention described herein may be manufactured and/or used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimedfis:

1. In a motion-picture projection machine, means for movingmotion-picture film across a concentrated beam of light with continuous-uniform velocity, means comprising an optical lens or lenses forforming primary images of the picture frames appearing on said fllm suchprimary images moving with a continuous uniform velocity, a multiplicityof reflective light-beam-inverting mechanisms comprising essentiallypairs of reflective surfaces making angles of approximately ninetydegrees with each other arranged to move across the beam of lightproducing the aforesaid moving primary images at a point along thelength of said beam as near as practicable to said primary images and sonear to 'said primary images as to practically eliminate the formationof double images caused by small errors in the 90 angle between the tworeflective surfaces of any of the said light-beam-inverting mechanisms,said mechanisms beingadapted `when so moved at a particular speed andwith a particular synchronization with respect to the aforesaidmovingmotion-picture film' to reflect the aforesaid light beam, stopping alltranslatory motion of saidvverting mechanisms for so synchronizing andcontrolling relative velocities of motion of the aforesaid film Iand theaforesaid light-beam-inverting mechanisms as to allowlight-beam-inverting mechanisms to perform the function described.

2. In a' motionpicture projection machine, means for movingmotion-picture film across a concentrated beam of light' withcontinuousuniform velocity, means comprising an optical len-s or lenses forforming primary'images of the picture frames appearing on said' film,'such primechanisms arranged to move across the beamlight-beam-invertlng of light producing the aforesaid moving primaryimages at a point along the length of said beam as near as practicableto` said primary images and so near to said images as to rendernegligible any irregular displacement of ,said primary images caused bysmall inaccuracies in the light-beam-inverting mechanisms, saidlight-beam-inverting mechanisms being adapted when so moved at aparticular speed and with a particular synchronization with respect tothe aforesaid moving motion-picture film to stop all translatory motionof said beam and thereby cause a stationary primary image to be formedconcentric with the central axis of said beam; means comprising aframing screen in the plane of the Aaforesaid primary images forintercepting all images except the aforesaid image that is concentricwith the central axis of the aforesaid beam, means comprising an opticallens or lenses for refocusing all light passing the aforesaid framingscreen to form a stationary secondary image on a motion-picturelprojection screen; and means interconnecting the aforesaid means formoving motion-picture film and the aforesaid light-beam-invertingmechanisms for so synchronizing and controlling relative velocities ofmotion of the aforesaid film and the aforesaid light-beam-invertingmechanisms as to allow light-beam-inverting mechanisms' to perform thefunction described.

3.`In a motion-picture projection machine, means for movingmotion-picture film across a concentrated beam of light with continuousuniform velocity; means comprising an optical lens or lenses for formingprimary images of the picture frames appearing on said film, suchprimary images moving with a continuous uniform velocity; a multiplicityof reflective light-beaminverting mechanisms, comprising essentiallypairs of reflective surfaces making an angle of approximately ninetydegrees with each other, arranged to move across the beam of lightproducing the aforesaid moving primary images at Y a point along thelength of said beam as near as practicable to said primary images and sonear to said primary images as to practically eliminate the formation ofdouble images caused by small errors in the 90 angle between the tworeflective surfaces of any of the said light-beaminverting mechanisms,said light-beam-inverting mechanisms being adapted 'when so moved at aparticular speed and with a particular synchronization with respect tothe aforesaid moving motion-picture film to reflect the aforesaid lightbeam, the reflected beammaking an angle with the incident beam in aplane perpendicular to the direction of motion of the aforesaid primaryimages, stopping all translatory motion of said beam and thereby causinga stationary primary image to be formed concentric with the central axisof said beam; means comprising a framing screen in the plane of theaforesaid primary images for intercepting all images except theaforesaid image that is concentric with the central axis of theaforesaid beam, means comprising an optical lens or lenses forrefocusing al1 light passing the aforesaid vframing screen to form astationary secondary image on a motion-picture projection screen, andmeans inter-v j connecting the aforesaid means for moving themotion-picture nlm and the aforesaid lightbeam-inverting mechanisms forso Vsynchronizing and controlling relative velocities of motion of theaforesaid film and the aforesaid lightbeam-inverting mechanisms las toallow lightbeam-inverting mechanisms to perform the function described.

4. In a 'motion-picture projection machine, means for movingmotion-picture film across a 5 concentrated beam of light withcontinuous uniform velocity; means for forming primary images of thepicture frames lappearing cn said lm, such primary images moving with acontinuous uniform velocity; a multiplicity of lightl0 beam-invertingmechanisms arranged to move across the beam of light producing theaforesaid moving primary images at a point along the length of said beamas near as practicable to said primary images and so near to said imagesas to render negligible any irregular displacement of said primaryimages caused by small inaccuracies in the light-beam-invertingmechanisms, said light-beam-inverting mechanisms being adapted when somoved at a particular vspeed and with a particular synchronization withrespect to the aforesaid moving motion-picture film to stop alltranslatory motion of said beam and thereby cause a stationary primaryimage to be formed concentric with the central axis of said beam; meansfor intercepting ail images except the aforesaid image that isconcentric with the central axis of the aforesaid beam: means forrefocusing all light not intercepted by the aforesaid means to form astationary secondary image on a motion-picture projection screen, andmeans interconnecting the aforesaid means for moving motion-picture filmand the aforesaid light-beam-inverting mechanisms for so synchronizingand controlling relative velocities of motion of the aforesaid film andthe aforesaid light-beam-inverting mechanisms as t0 allowlight-beam-inverting mechanisms to perform the function described,

5. In a motion-picture projection machine,

means for'moving motion-picture film across a concentrated beam of lightwith continuous uniform velocity; means for forming primary images ofthe picture frames appearing on said nlm, such primary images movingwith. a continucus uniform velocity; a multiplicity of reectivelight-beam-inverting mechanisms comprising pairs of reflective surfacesmaking angles with each other adjustable to a value of ninety degreeswithin close limits and arranged to move across the beam of lightproducing the aforesaid moving primary images at a point along thelength of said beam as near as practicable to said primary images and sonear to said primary images as to practically eliminate the formation ofdouble images caused by small errors in the 90 angle between the tworeflective surfaces o! any of said light-beam-inverting mechanisms, saidlight-beam-inverting mechanisms being adapted when so moved at aparticular speed and with a particular synchronization with respect tothe aforesaid moving motion-picture film to reflect the aforesaid lightbeam, stopping al1 translatory motion of said beam and *thereby causinga stationary primary image to c5 be formed concentric with the centralaxis of said beam; means for intercepting all images except theaforesaid image that is concentric with the central axis of theaforesaid beam: means for refccusing al1 light not intercepted by 70,theaforesaid means to'form a stationary secondary image on a motion-pictureprojection screen, and means interconnecting the aforesaid means formoving the motion-picture film 'and the aforesaid light-beam-invertingmechanisms for so synchronizing and controlling relative velocities ofthe aforesaid-nlm and the aforesaid light-beam-inverting mechanisms asto allow light-beam-inverting mechanisms to perform the functiondescribed.

6. In a motion-picture projection machine, means for movingmotion-picture film across a concentrated beam of light with continuousuniform velocity; means for forming images of the picture framesappearing on said film, such images moving with a` continuous uniformvelocity; a multiplicity of reflective light-beaminverting mechanismscomprising pairs of reectiv'e surfaces making angles with each otheradjustable to a value of ninety degrees within close limits and arrangedto move across the beam of light producing the aforesaid moving imagesat a point along the length of said beam Ias near as practicable toaforesaid moving images and so near` to aforesaid moving images as topractically eliminate the formation of double images caused by smallerrors in the 90 angle between the two reflective surfaces of any of thesaid light-beam-inverting mechanisms, said light-beam-invertingmechanisms being adapted when so moved at a particular speed and with aparticular lsynchronization with respectl to the aforesaid movingmotion-picture v film to reflect the aforesaid light beam, stopping alltranslatory motion of said beam and thereby causing a stationary imageto be formed concentric with the central axis of said beam, and meansinterconnecting the aforesaid means for moving motion-picture nlm andthe aforesaid light-beam-inverting mechanisms for so synchronizing andcontrolling relative velocities of motion of the aforesaid lm and theafore- Vsaid light-beam-inverting mechanisms as to allowlight-beam-inverting mechanisms to perform the function described.

'1. In a motion-picture projection machine, means for movingmotion-picture nlm across a concentrated beam of light with continuousuni-y form velocity; means for forming primary images of the pictureframes appearing on said film, tuch primary images moving with acontinuous uniform velocity; a multiplicity of light-beaminvertingmechanisms arranged to move across the beam of light producing theaforesaid moving primary images at a point along the length of said beamas near as practicable to the aforesaid primary images and so near tothe aforesaid primary images as to render negligible any irregulardisplacement of the aforesaid primary stationary image to be formedconcentric withf the central axis of said beam; means for refocusing alllight that passes through the aforesaid stationary image that isconcentric with the central axis of the aforesaid beam to form astationary secondary image on a motion-picture projection screen, andmeans interconnecting the aforesaid means for moving motion-picture filmand the aforesaid light-beam-inverting mechanisms for so synchronizingand controlling relative velocities of motion `of the aforesaid film andthe aforesaid light-beam-inverting mechanisms as to allowlight-beam-inverting mechanisms to perform the function described.

8. In a motion-picture projection machine, means for movingmotion-picture film across a concentrated beam of light with continuousuniform velocity; mean's for forming images of the picture framesappearing on said nlm, such images moving with a continuous uniformvelocity, a multiplicity of light-beam-inverting mechanisms arranged tomove across the beam of light producing the aforesaid moving images at apoint along the length of said beam as near as practicable to theaforesaid moving images and Iso near to aforesaid moving images as torender negligible any displacement of the aforesaid moving -imagescaused by small inaccuracies in the light-beam-inverting mechanisms,said light-beam-inverting mechanisms being adapted when so moved at aparticular speed and with a particular synchronization with respect tothe aforesaid moving motion-picture lm to 'stop all translatory motionof said beam and thereby cause a stationary image to be formedconcentric With the central axis of said beam, and means interconnectingthe aforesaid means for moving motion-picture vfilm and the' aforesaidlightbeam-inverting mechanisms for sovsynchronizing and controllingrelative velocities of motion of the aforesaid lm and the aforesaidlightbeam-inverting mechanisms as to allow lightbeam-invertingmechanisms to perform the function described.

CEARCY D. MILLER.

